1. Field of the Invention
The present invention relates to a manufacturing method for a photomask for wafer processing.
2. Description of the Related Art
A plurality of devices such as ICs and LSIs are formed on the front side of a semiconductor wafer so as to be separated by a plurality of division lines. The back side of the semiconductor wafer is ground to reduce the thickness of the semiconductor wafer to a predetermined thickness. Thereafter, the semiconductor wafer is divided along the division lines by a dicing apparatus or a laser processing apparatus to thereby obtain the individual devices as chips. These devices are widely used in various electronic apparatuses such as mobile phones and personal computers. However, in the case of dicing the semiconductor wafer by using a dicing saw, a cutting blade is rotated at a high speed and fed into the division lines of the semiconductor wafer, causing a problem such that chipping may occur on the devices due to a crush force by the cutting blade, so that the die strength of each device may be reduced.
Further, in dicing the semiconductor wafer by using the cutting blade, it is necessary to accurately align the cutting blade with each division line and then cut each division line, so that this cutting operation is inefficient. Particularly in the case that the size of each device is small and the number of division lines is therefore large, much time is required to cut all of the division lines, causing a reduction in productivity. To improve the die strength of each device or improve the productivity, Japanese Patent Laid-Open No. 2006-114825 has proposed a technique of plasma-etching the division lines of a semiconductor wafer to thereby divide the wafer into the individual devices.